Fabrication, magnetic, and ferroelectric properties of multiferroic BiFeO3 hollow nanoparticles

Hollow BiFeO3 nanoparticles were synthesized by an electrospray route for the first time. The

phase purity and structure have been investigated by x-ray diffraction and Raman spectroscopy.

Transmission and scanning electron microscope investigations revealed that the as-obtained

BiFeO3 hollow spheres were polycrystalline, with a shell thickness of 35 nm. The formation

mechanism can be possibly explained by Ostwald ripening. Raman spectra have verified decreased

vibrational frequencies in BiFeO3 nanoparticles. These hollow and core-shell multiferroic

nanoparticles exhibit significantly enhanced ferromagnetism from 5 to 600 K due to a broken spiral

spin structure. The ferroelectricity of hollow BiFeO3 particles exhibits a lower switching electric

field, which is confirmed by Kelvin probe force microscopy.